Listmania!
10 Books for Electronic Engineering
The Art of ElectronicsThe Art of Electronics by Paul Horowitz
Buy new: £43.39 / Used from: £35.00
A little dated on the digital and micros side but still one of the best electronics reference books
Digital Communications: Fundamentals and ApplicationsDigital Communications: Fundamentals and Applications by Bernard Sklar
Buy new: £36.64 / Used from: £31.99
One of many good communications books
Understanding Digital Signal ProcessingUnderstanding Digital Signal Processing by Richard G. Lyons
Buy new: £38.69 / Used from: £39.78
Buy this DSP book before any other, now in the second edition
Digital Design: Principles and Practices (Prentice Hall Xilinx design series)Digital Design: Principles and Practices (Prentice Hall Xilinx design series) by John F. Wakerly
Buy used from: £5.97
The best general digital design book; Boolean logic, VHDL, FPGAs, CPLDs etc.
An Embedded Software PrimerAn Embedded Software Primer by David E. Simon
Buy new: £24.75 / Used from: £24.39
Easy to read introduction to embedded systems and real time operating systems (RTOS)
The  C Programming Language (2nd Edition)The C Programming Language (2nd Edition) by Brian W. Kernighan
Buy new: £19.16 / Used from: £10.50
The C programming book
Design with Operational Amplifers and Analog Integrated Circuits (Mcgraw-Hill Series in Electrical and Computer Engineering)Design with Operational Amplifers and Analog Integrated Circuits (Mcgraw-Hill Series in Electrical and Computer Engineering) by Sergio Franco
Buy used from: £40.00
Great coverage of analogue topics; op amps, filters, data converters, PLLs etc
Power Electronics: Converters, Applications and Design, Media EnhancedPower Electronics: Converters, Applications and Design, Media Enhanced by Ned Mohan
Buy used from: £190.90
The classic power electronics book, 3rd edition
The Circuit Designer's Companion (EDN Series for Design Engineers)The Circuit Designer's Companion (EDN Series for Design Engineers) by Tim Williams
Buy new: £29.34 / Used from: £30.34
Grounding and wiring, analogue and digital components, PCBs, EMC, power supplies, general product design etc
High Speed Digital Design: A Handbook of Black MagicHigh Speed Digital Design: A Handbook of Black Magic by Howard W. Johnson
Buy new: £53.54 / Used from: £29.75
Essential reading for high speed digital designers, also check out the sequel: Advanced Black Magic